1. Field of the Invention
The present invention relates to a structure of a paper feed tray for use in an image forming apparatus, such as a printer, a copying machine, a facsimile machine, and a composite machine thereof.
2. Description of the Related Art
A paper feed tray of an image forming apparatus comprises components, such as a casing, a paper loading plate provided on the bottom portion of the casing for loading paper thereon, a side guide for regulating a side portion of a sheet of paper, an end guide for determining a position of a tail edge of a sheet of paper, a paper separating claw for separating paper sheet by sheet, a retard roll, and a casing attaching/detaching handle. Trays each enabled to accommodate 250 sheets of paper (that is, a half pack) or more need to ensure sufficient stiffness thereof. Further, there is necessity for assembling each of components into the tray with good accuracy so that sheet conveying performance is maintained even when a sheet conveying speed is increased to a high value. Therefore, a paper feed tray according to the related art necessarily has a structure in which many screws are tightened. This results in complex assembling and increase in cost of the tray. Moreover, when being conscious of recycling of the tray, disassembling thereof requires a great deal of labor in case that there are many places, to each of which a screw is fastened, in the tray. Simultaneously, it takes time and labor to sort out individual members thereof into a group of members to be recycled and another group of members to be scrapped.
Furthermore, generally, the greater part of the paper feed tray is made of a resin so as to reduce the cost and weight thereof. When being conscious of reuse of each of components of the paper feed tray, it is necessary to disassemble the paper feed tray without damaging the components made of a resin. When screws are fastened to the components made of a resin, screw holes are damaged during the disassembling of the paper feed tray. Thus, it is difficult to reassemble the paper feed tray by using the same screw holes.
In view of such circumstances, an object of the invention is to substantially improve the structure of a paper feed tray for use in an image forming apparatus and to provide a paper feed tray that is easily assembled and disassembled and that is rational in relation recycling, reuse, and disposal.
The invention is accomplished to solve the aforementioned problems. According to a first aspect of the invention, there is provided a paper feed tray comprising a casing, a paper loading plate for loading paper thereon, the paper loading plate provided on a bottom portion of the casing, a side guide for regulating a side portion of a sheet of paper, an end guide for determining a position of a tail edge of a sheet of paper, a paper separating member for separating paper sheet by sheet, a casing attaching/detaching handle, an operation tab for operating the side guide, and a catching portion for catching the paper separating member, the catching portion formed between the side guide and the operation tab. In this case, it is preferable that the paper separating member is a paper separating claw and a fulcrum of the paper feed claw is formed to be integral with a shaft for fitting the operation tab into the side guide. Further, it is preferable that a snap is disposed so that a force received by the paper separating claw from paper during supply of paper acts in a direction in which snap-fitting performed on the operation tab to be utilized at assembling of the tray does not become off. Furthermore, a paper feed tray of the invention may have a structure which includes a slit portion that elastically opens and tentatively holds a paper separating claw in a retreat position and is formed between an operation tab member and a side guide as means for avoiding a paper separating claw serving as a hindrance to assembling of a paper loading plate. The invention provides a paper feed tray having a structure that comprises a regulating member for regulating a movable range of the paper separating claw so as to satisfy paper feed performance. In this tray, this regulating member has a structure adapted to bend owing to the elasticity thereof. Further, when assembling the tray, the regulating member bends in such a way as to prevent the paper separating claw from interfering with another member to avoid the paper separating claw. At that time, the paper separating claw and the regulating member may be placed so that even when the regulating member for regulating the movable range of the paper separating claw is bent by a force, which is received by the regulating member during the supply of paper, the separating claw is firmly regulated in a direction in which the separating claw is prevented from escaping from a normal position thereof to be regulated.
Further, according to a second aspect of the invention, there is provided a paper feed tray comprising a tray body, a drawer handle member provided on the tray body, for attaching/detaching the tray body to/from an image forming apparatus, the drawer handle member constituting a part of an exterior cover of the image forming apparatus, and a fixing member having an elastic piece and an engaged portion, wherein the elastic piece is elastically deformable, has an engaging portion, and is provided on one of the tray body and the drawer handle member, the engaged portion and is provided on the other thereof, the tray body and the drawer handle member comprise at least two constituent members, the engaging portion and the engaged portion is engaged with each other to fix the tray body and the drawer handle member to each other. At that time, it is preferable that the fixing member consists of the elastic piece and the engaged portion. Further, it is preferable that when the tray body is attached to and detached from the image forming apparatus, a direction of a force applied to the fixing member is different from a direction in which the engaging portion is engaged with the engaged portion. Moreover, it is preferable that when the tray body is lifted by holding the drawer handle member, a direction of a force applied to the fixing member is different from a direction in which the engaging portion is engaged with the engaged portion. Furthermore, a direction in which the engaging portion is engaged with the engaged portion may be substantially perpendicular to a direction in which the tray body is attached to and detached from the image forming apparatus. Further, it is preferable that the tray body and the drawer handle member are made of different synthetic resins and the synthetic resin constituting the tray body is a more durable material than that constituting the drawer handle member. Moreover, it is preferable that the paper feed tray further comprises a pair of plate-like arm members provided at both end portions of the drawer handle member, respectively, the plate-like members extended in a direction in which the tray body is attached to and detached from the image forming apparatus, wherein a force received from the tray body is applied to each of the arm members in a direction perpendicular to a direction of thickness thereof. Furthermore, wherein each of the arm members may be provided to abut against a wall surface that is provided on a sidewall of the tray body and extends in a direction substantially perpendicular to the direction in which the tray body is attached to and detached from the image forming apparatus. Incidentally, it is preferable that a space is provided adjacent to the elastic piece. Preferably, the space is a concave portion provided in the sidewall of the tray body.
Further, according to a third aspect of the invention, there is provided A paper feed tray comprising a tray body, a drawer handle member provided on the tray body, for attaching/detaching the tray body to/from an image forming apparatus and, the drawer handle member constituting a part of an exterior cover of the image forming apparatus, a fixing member for fixing the tray body and the drawer handle member to each other, provided on one of the tray body and the handle drawer member, an arm member having a plate-like shape, being elastically deformable, and extending in a direction in which the tray body is attached to and detached from the image forming apparatus, a fixing portion for positioning and fixing the arm member, provided on the other thereof. In this case, it is preferable that the arm member is provided to be parallel to a sidewall of the tray body and the fixing portion abuts against a plate-thickness surface of the arm member to position and fix the arm member. Further, it is preferable that the arm member is elastically deformable in a direction substantially perpendicular to a direction in which the tray body is attached to and detached from the image forming apparatus.
Next, the invention provides another paper feed tray, which comprises a regulating member, provided in an end guide enabled to correspond to a plurality of paper lengths and to easily move, for holding a base of the end guide and for regulating a moving operation in such a way as to prevent the end guide from slipping off. In this tray, the regulating member is a member adapted to have elasticity in itself. In this tray, the regulating member for holding the base of the end guide and for regulating a moving operation in such a way as to prevent the end guide from slipping off may be a member adapted to be bent when attached to and detached, and to enable the end guide to easily move without detaching the end guide.
It is preferable that the elastic member having elasticity is a resin sheet member. Further, a regulating member, which is provided in an end guide enabled to correspond to a plurality of paper lengths and to easily move, for holding the base of the end guide and for regulating a moving operation in such a way as to prevent the end guide from slipping off, may be a member to be assembled from assembly members each having elasticity so as to easily assemble the tray by utilizing the elasticity without a tool.
Another paper feed tray is preferable, in which the members each serving as the assembly member and having elasticity in itself are easily assembled into the regulating member without a tool by utilizing the elasticity, and has a part to be bent when assembled, and another part to be bent when operated by a user, and in which the part to be bent when assembled, and the part to be bent when operated by a user are formed separately from each other.
Another preferable paper feed tray may have a structure in which a projection portion, provided on a retard roll holding member, for regulating an own position, and an attachment-side positioning member having elasticity. When the tray is assembled, the attachment-side positioning member is pushed up by the projection portion provided on the retard roll holding member for regulating the position, so that the positioning member is enabled to move to a normal position.
As described above, according to the invention, all the attaching members for attaching constituent members of the tray to one another have a snap-fit structure to thereby enable easy assembling and disassembling thereof. Further, the paper feed tray is constituted only by members that enable all steps of processes of assembling and disassembling the tray to be performed from the same direction without changing orientation of the tray. Consequently, the invention contributes to reduced labor and cost.